Device for automatically regulating aircraft power plant gas generator and free turbine speeds as a function of heating, electricity generation, noise emission, and fuel consumption

ABSTRACT

A regulator device for automatically regulating a power plant of a rotary wing aircraft having a turbine engine includes a computer system. The computer system, while implementation of an idling mode of operation of the turbine engine is requested and the aircraft is standing on ground, implements the idling mode of operation and operates the turbine engine in compliance with idling mode of operation as a function of operational and hierarchically ordered conditions either through a first mode of regulation by regulating a speed of rotation (Ng) of a gas generator of the turbine engine or through a second mode of regulation by regulating a speed of rotation (NTL) of a free turbine of the turbine engine.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/273,805, filed Sep. 23, 2016, now U.S. Pat. No. 10,526,977, which isa divisional of U.S. patent application Ser. No. 13/753,690, filed Jan.30, 2013, now U.S. Pat. No. 9,476,360, which claims priority to FrenchPatent Application No. FR 12 00353, filed Feb. 7, 2012; the disclosuresof which are incorporated in their entirety by reference herein.

BACKGROUND OF THE INVENTION (1) Field of the Invention

The present invention relates to a method of automatically regulating anaircraft power plant, to a device, and to an aircraft.

More particularly, the invention is applicable to a rotary-wingaircraft.

(2) Description of Related Art

Conventionally, a rotary wing aircraft is equipped with a power plantcomprising at least one engine such as a piston engine or a turbineengine. Such a turbine engine may also be referred to as a “turboshaftengine”.

A gearbox connects the power plant to the main advance and lift rotor:this is referred to as the “main gearbox” or “MGB”.

Temperature limits for an engine and torque limits for an MGB serve todefine an operating envelope for each engine that covers two normalutilization ratings:

a takeoff rating corresponding to a level of torque for the MGB and alevel of heating for the engine that can be accepted for a limitedlength of time without significant degradation, this takeoff ratingbeing defined by a maximum takeoff power PMD and by a duration for usingthis maximum takeoff power that is generally of the order of fiveminutes; and

maximum continuous rating, which rating is defined by a maximumcontinuous power PMC corresponding to about 90% of the maximum takeoffpower PMD, and by a utilization duration for said maximum continuouspower that is generally unlimited.

In addition, manufacturers define an idling rating for minimizing fuelconsumption, with the engine nevertheless continuing to keep runningwhile idling.

The idling rating for an aircraft engine is a particular mode ofoperation enabling the engines of the aircraft to operate on the groundwhile minimizing the nuisance and/or while maximizing the comfort of thepeople and crew moving around the aircraft. In particular, the idlingrating serves to:

keep the engine up to temperature for rapid departure;

minimize the noise emitted by the aircraft;

minimize pollutant emission and fuel consumption; and to enableelectricity to be generated on board and hot air to be taken for thepurpose of heating and demisting the cabin.

The idling rating is therefore a relatively complex mode, havingobjectives that can be opposing and constrained. For example, the liftrotor of a helicopter must be driven by a turbine engine operating at anidling rating that is relatively low in order to minimize noise, but itis also necessary for the engine to have an idling rating that isrelatively high in order to enable an electricity generator to operate.

The ratings enabling the aircraft to operate in flight are, forconvenience, referred to as “flight ratings”, whereas the ratingenabling the engine to idle is referred to as the “idling rating”.

The aircraft is then provided with a physical state selector havingthree stable positions. These three positions for the state selectorare: engines stopped or “STOP”; engines in idling mode or “IDLE”; andengines in flight mode or “FLY”.

This manual state selector (STOP/IDLE/FLY) thus makes it possible toindicate to an on-board engine computer in the aircraft:

to stop each engine when the selector is in the “STOP” position;

to implement the idling rating when the selector is in the “IDLE”position; and

to implement a flight rating when the selector is in the “FLY” position.

Therefore, when the pilot positions the selector in the “IDLE” position,the engine computer of an engine regulates said engine so as to cause itto operate in compliance with the idling rating defined by themanufacturer.

In a first example, an engine computer regulates the first speed ofrotation Ng of the gas generator of the engine.

Thus, an engine computer acts, in particular, on a fuel metering deviceof the engine to make the first speed of rotation Ng tend towards asetpoint speed of rotation Ng*.

That first example offers the advantage of guaranteeing a setpoint speedof rotation of the gas generator that enables some minimum amount ofmechanical power to be extracted (taken off) and some minimum amount ofhot air to be extracted (taken off).

Such a minimum extraction of hot air may be determined to ensure heatingand/or demisting of a cabin of the aircraft.

In addition, this first example prevents any untimely takeoff of theaircraft while the idling mode is engaged. If a pilot increases thecollective pitch of the blades of the rotary wing, then the powerdelivered by the engine does not increase. On the contrary, the secondspeed of rotation of the free turbine and the speed of rotation of therotor decrease.

Since the second speed of rotation NTL of the free turbine and the firstspeed of rotation Ng of the gas generator vary, the noise generated bythe aircraft is not controlled. In addition, the rotary wing might finditself within an operating range that might induce a phenomenon ofground resonance.

By way of a variant, in a second example, an engine computer regulatesthe second speed of rotation NTL of a free turbine of the engine.

Thus, an engine computer acts, in particular, on a fuel metering deviceof the engine to make the second speed of rotation NTL tend towards asetpoint speed of rotation NTL*.

That second example offers the advantage of ensuring a speed of rotationfor the rotor of the helicopter that is constant. The above-mentioneddrawbacks are then avoided.

Unfortunately, the first speed of rotation Ng can vary without saidfirst speed being controlled by the regulation system. The first speedof rotation Ng can then become insufficient to enable a minimum amountof mechanical power to be extracted and a minimum amount of hot air tobe extracted.

Finally, the setpoint used for the second speed of rotation is generallyless than the nominal speed for the rotary wing in flight.

If a pilot accidentally changes the collective pitch of the blades ofthe rotary wing, the first speed of rotation Ng increases. The powerdeveloped by the engine is increased accordingly. The aircraft mightthen take off with a second speed of rotation that is potentially toolow.

Therefore, that state of the art requires pilots to determine inintentional manner whether they wish to implement an idling rating viaan idling mode or a flight rating via a flight mode. Depending on theaircraft, the idling rating is, in addition, implemented by regulatingthe speed of rotation of the gas generators of the engines or byregulating the speed of rotation of the free turbines of the engines.

In addition, if a slight increase in power is necessary for a secondaryneed (more heating, an increased electricity need, etc.), the pilot mustswitch the regulation of the engine over to the flight mode ofoperation.

In the aviation sector, various documents mention automated monitoringand control of operation of a power plant while idling.

Thus, Document US 2011/0208400 describes the use of a selector having an“IDLE” position and a “MAXPOWER” flight position in the context ofelectronic control for adjusting operation of an aircraft turbopropengine. A man-machine interface thus enables the pilot to choose a modeof operation for the turboprop, between a free power delivery mode ofoperation and an idling mode of operation.

Weight-on-Wheels (WoW) information from a sensor for sensing that theaircraft is on the ground is taken into account in order to define anidling rating.

Document U.S. Pat. No. 5,363,317 describes monitoring failures in amulti-engine aircraft. In the event of a failure being detected in oneof the engines, the remaining engine is controlled accordingly. Thisleads to regulation as a function of conditions representing a flightstate of the aircraft, passing either to a flight idle or to a groundidle.

Document U.S. Pat. No. 4,541,237 describes sub-idle speed control for anaircraft. Two ground idle modes are described, but the regulationaccording to that document makes no provision for automatic andcontextual switching between idling and sub-idling modes. That documentmakes provision to reduce power in sub-idling mode in order to reducethe thrust from the engine.

Document U.S. Pat. No. 5,403,155 describes managing power from ahelicopter turbine. To enable the pilot to pass manually between anormal state and an off state, touch interfaces are provided.

Document U.S. Pat. No. 4,500,966 describes “super contingency” controlfor a helicopter on which the speed of rotation of the main rotor is toolow as a result of an engine failure.

Document WO 2000/039442 also describes a system for regulating anairplane or helicopter engine.

BRIEF SUMMARY OF THE INVENTION

An object of the invention is therefore to provide a method ofautomatically regulating an aircraft power plant, which method serves tooptimize the operation of the aircraft.

The invention provides a method of automatically regulating a powerplant of an aircraft in an idling mode of operation, said power plantcomprising at least one turbine engine, said aircraft possibly having atleast one rotary wing provided with a plurality of blades havingvariable pitch and driven in rotation by said power plant, it beingpossible for each engine to operate in an idling mode of operation andin a flight mode of operation. Each engine also comprises a gasgenerator and a free turbine.

Under such circumstances, during a selection stage, an idling mode ofoperation is selected.

For example, it is possible to move a three-position selector making itpossible to select an engine-stopped mode of operation, and idling modeof operation, and a flight mode of operation.

As a variant, it is possible to operate a two-position selector forselecting an engine-stopped mode of operation or an engine-on mode ofoperation. The engine-on mode of operation makes it possible to selectautomatically the idling mode of operation or the flight mode ofoperation, depending on criteria defined by the manufacturer.

Furthermore, during a regulation stage, an idling mode of operation isimplemented as a function of operational and hierarchically orderedconditions:

either through a first mode of regulation by regulating a first speed ofrotation of the gas generator of each engine;

or through a second mode of regulation by regulating a second speed ofrotation of the free turbine of each engine.

In the first mode of regulation, the flow rate of fuel delivered to theengine is increased or reduced so that the first speed of rotation tendstowards a setpoint.

Conversely, in the second mode of regulation, the flow rate of fueldelivered to the engine is increased or reduced so that the second speedof rotation tends towards a setpoint.

Unlike the prior art, each engine when idling may operate in a first ora second mode of regulation, and not in only a single mode ofregulation.

Under such circumstances, depending on the operational andhierarchically ordered conditions defined by the manufacturer, theengine is regulated as a function of its first or its second speed ofrotation.

The invention thus makes it possible to optimize the operation of theengine while idling.

The method may also include one or more of the following additionalcharacteristics.

For example, these operational and hierarchically ordered conditions maybe selected from a list including:

generation of hot air from the engine for heating the aircraft as afunction of outside conditions;

generation of electricity from the gas generator for electricallypowering the aircraft;

minimization of noise emission; and

minimization of fuel consumption.

It should be observed that it is also possible to establish a priorityorder as a function of the needs of the operator of the aircraft.

Optionally, the operational and hierarchically ordered conditions are inthe following order:

generation of hot air from the engine for heating the aircraft as afunction of outside conditions;

generation of electricity from the gas generator for electricallypowering the aircraft;

minimization of noise emission; and

minimization of fuel consumption.

It is thus possible automatically to give priority firstly to hot airgeneration, and then to electricity generation from the gas generator,to minimizing noise generation, and to minimizing fuel consumption.

To this end, an original first speed of rotation is determined that isto be reached for regulating the second speed of rotation at a leveldefined by the manufacturer in order to satisfy a first operationalcondition.

This level may be defined to ensure that the aircraft operates outside aground resonance range of the rotorcraft.

In other words, the manufacturer defines a second critical speed ofrotation that minimizes the risks of a ground resonance phenomenonappearing.

As a function of the outside conditions, the first original speed ofrotation is deduced automatically.

Under such circumstances, a target is determined for the electricitylevel to be delivered by the power plant of the engine in order tosatisfy a second operational condition. For example, the electriccurrent consumed by the aircraft is determined. It can be understoodthat the second operational condition is considered as being moreimportant than the first operational condition.

Each engine must then deliver a target current equal to said consumedelectric current divided by the number of engines, for example.

If the power plant cannot deliver said electricity generation targetwhen each gas generator is operating at said first original speed ofrotation, the idling mode of operation is implemented by regulating thefirst speed of rotation of said gas generator in the first mode ofregulation.

Increasing the amount of mechanical power that is extracted to generateelectricity tends to slow down the first speed of rotation of the gasgenerator of the engine. A reduction that is too large results in theengine being shut down.

The manufacturer thus gives preference to regulating the first speed ofrotation of the gas generator in order to avoid said engine shuttingdown.

More precisely, if the power plant cannot deliver said electricitygeneration target when each gas generator is operating at said firstoriginal speed of rotation:

a setpoint hot air temperature is determined that is to be delivered forheating the aircraft in order to satisfy a third operational conditionconsidered as being more important than the second operationalcondition;

a first setpoint speed of rotation is determined that makes it possibleto deliver said electricity generation target;

it is determined whether the first setpoint speed of rotation makes itpossible to reach the setpoint hot air temperature;

if the first setpoint speed of rotation makes it possible to reach saidsetpoint hot air temperature, the engine is controlled in order tomaintain the first speed of rotation equal to the first setpoint speedof rotation in the second mode of regulation; and

if the first setpoint speed of rotation does not make it possible toreach said setpoint hot air temperature, the engine is controlled inorder to maintain the first speed of rotation equal to a first targetspeed of rotation making it possible to reach said setpoint hot airtemperature.

Conversely, if the power plant can deliver said electricity generationtarget when each gas generator is operating at said first original speedof rotation:

a setpoint hot air temperature is determined that is to be delivered forheating the aircraft in order to satisfy a third operational condition;

if the first original speed of rotation makes it possible to reach saidsetpoint hot air temperature, the engine is controlled in order tomaintain the second speed of rotation equal to said level; and

if the first original speed of rotation does not make it possible toreach said setpoint hot air temperature, the first setpoint speed ofrotation making it possible to reach said setpoint hot air temperatureis determined, and then the engine is controlled in order to maintainthe first speed of rotation equal to the first setpoint speed ofrotation.

In another aspect, it is possible to implement inhibit means forinhibiting the first mode of regulation.

If the operator of the aircraft wishes to minimize the noise and/or thefuel consumption of the aircraft to the detriment of charging theon-board batteries or to the detriment of the inside temperature, forcedmanual selection of the second mode of regulation can thus beimplemented.

In addition, it is possible to implement a stop for limiting torquedeveloped by an outlet shaft of said engine when the engine is operatingin the idling mode of operation.

The stop prevents each engine from delivering torque greater than orequal to the torque necessary for the aircraft to take off at itsminimum weight.

Thus, there is no risk of the second mode of regulation inducingaccidental takeoff.

Two approaches are then possible:

either the torque limit is implemented in conservative manner so as toprevent takeoff under the conditions that are most favorable to takeoff(very dense air, low altitude, and low temperature);

or the torque limit is computed on the basis of the outside pressure andoutside temperature information.

The second approach can be necessary when the torque necessary fortakeoff under favorable conditions (cold weather, low altitude) is lessthan the torque necessary for maintaining an idling rating underunfavorable conditions (hot weather, and high altitude).

The stop may be of the type implemented for flight operating ratings.The stop may then be implemented by software means, by analog means, orby hydro-mechanical means.

Although it is common to implement a torque stop when implementing aflight rating that can generate high torque in order to protect amechanical assembly, implementing such a stop for an idling rating of anidling mode of operation in order to avoid inappropriate takeoff appearssurprising.

In addition to a method, the invention also provides a regulation devicefor regulating a power plant of an aircraft, said power plant comprisingat least one turbine engine, it being possible for each engine tooperate in an idling mode of operation and in at least one flight modeof operation.

This regulation device comprises:

a selector for requesting in particular the implementation of the idlingmode of operation; and

a computation system connected to the selector for controlling eachengine, said computation system executing stored instructions forimplementing the idling mode of operation as a function of operationaland hierarchical conditions:

either through a first mode of regulation by regulating a first speed ofrotation Ng of said gas generator;

or through a second mode of regulation by regulating a second speed ofrotation NTL of said free turbine.

This device may have one or more of the following characteristics.

For example, the calculation system may have an avionics computerconnected to a determination system for determining a collective pitchof the rotary wing as well as to a determination device for determininga state in which the aircraft is standing on the ground, and to theselector, said computation system including one engine computer perengine, which computer is connected to the avionics computer.

In addition, the aircraft has an electrical network electrically poweredby the power plant, and the regulation device optionally comprises ameasurement system for measuring the electricity consumed by saidelectrical network.

In addition, the regulation device may further comprise a measurementdevice for measuring the conditions of the surroundings outside theaircraft in order to determine a setpoint hot air temperature forheating the aircraft.

In addition, it is possible to implement inhibit means for inhibiting afirst mode of regulation of an idling mode of operation.

Finally, the invention provides an aircraft provided with a power plantcomprising at least one turbine engine, said aircraft possibly having atleast one rotary wing provided with a plurality of blades havingvariable pitch and driven in rotation by said power plant, it beingpossible for each engine to operate in an idling mode of operation andin at least one flight mode of operation.

This aircraft then includes a regulation device of the above-describedtype.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF DRAWINGS

The invention and its advantages appear in greater detail from thefollowing description of implementations given by way of illustrationwith reference to the accompanying figures, in which:

FIG. 1 is a view of an aircraft of the invention; and

FIG. 2 is a diagram explaining the method of the invention.

Elements present in more than one of the figures are given the samereferences in each of them.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an aircraft 1 provided with a rotary wing 300.

The aircraft 1 includes a power plant 3′. This power plant 3′ includesat least one turbine engine 3 for driving the rotary wing 300 via a maingearbox 2.

Each engine has a gas generator 4 and a free turbine 7. For example, thegas generator comprises a compressor 5 co-operating with a high-pressureturbine 6 that is arranged upstream from the free turbine 7.

The free turbine 7 is then connected to the main gearbox via apowertrain 9. For example, this powertrain 9 may be provided with anoutlet shaft that is set into rotation by the free turbine.

In addition, the aircraft is provided with mechanical power extraction(takeoff) means 100 for extracting mechanical power.

These mechanical power extraction means 100 may be constituted byelectrical equipment of the electricity generator type. The mechanicalpower extraction means 100 are then driven in rotation by the gasgenerator 4 via a shaft 100′.

The mechanical power extraction means 100 can thus operate in a motormode in order to perform a starter function.

The mechanical power extraction means 100 then communicate electricallywith an electrical network 40 of the aircraft, e.g. with an “electricalcore” 41.

In addition, the aircraft is provided with air extraction means 105 forextracting hot air from each engine.

The aircraft 1 is also provided with a regulation device 10.

Thus during a selection step STP0, a pilot operates a selector inparticular in order to request implementation of an idling mode ofoperation.

By way of example, the pilot operates a two-position selector either tostop each engine or to set each engine 3 into operation.

With reference to FIG. 1, the regulation device 10 then includes aselector 60 having a first position POS1 requesting each engine 3 tostop and a second position POS2 requesting each engine 3 to operate.

To this end, the regulation device 10 is provided with a computationsystem 15 connected to the selector 60 for the purpose of controllingeach engine 3.

This computation system includes at least one computation member thatexecutes instructions stored in a non-volatile memory on a storagemedium for the purposes of stopping the engines or of causing them tooperate.

With reference to FIG. 2, during a regulation step STP1, each engine 3is controlled automatically so as to implement the idling mode ofoperation of the engines 3 if the collective pitch CLP of the blades 301of the rotary wing is less than a threshold and if the aircraft 1 isstanding on the ground.

During a selection substep STP1.0, it is verified whether the followingtwo criteria are satisfied:

the collective pitch CLP of the blades 301 is less than a threshold; and

the aircraft 1 is standing on the ground.

The criterion relating to the state in which the aircraft is standing onthe ground may, in addition, be associated with a delay time.

If one of the two criteria is not satisfied, the computation system 15requests a flight mode of operation FVOL to be implemented.

Conversely, if both of the criteria are satisfied, the computationsystem 15 automatically requests the engines 3 to operate in an idlingmode of operation.

With reference to FIG. 1, the regulation device then includes aconventional determination system 50 for determining the collectivepitch of the blades and a conventional determination device 55 fordetermining a state in which the aircraft is standing on the ground.

Reference may be made to the literature in order to obtain informationabout such a determination system 50 and such a determination device 55.

The computation system 15 is then connected to the determination system50 as well as to the determination device 55 and to the selector 60, thecomputation system 15 executing instructions stored in a memory for thepurpose of automatically implementing the idling mode of operation ineach engine 3 if a collective pitch CLP of the blades 301 is less than athreshold and if the aircraft 1 is standing on the ground.

The computation system 15 may have one engine computer 20 per engine,such as an engine computer of the “Full Authority Digital EngineControl” (“FADEC”) type.

This engine computer 20 then has a computation unit 21 and a memory 22storing instructions that can be executed by the computation unit 21.

In addition, the computation system 15 may be provided with an avionicscomputer 30 provided with a computation member 31 and with storage means32 that store instructions. The avionics computer 30 is then connectedto the determination system 50 as well as to the determination device 55and to the selector 60.

If the two above-explained criteria are satisfied, the avionics computer30 then sends a request for operating in an idling mode of operation toeach engine computer 20. Each engine computer then regulates theassociated engine in order to satisfy that request.

In usual manner, the engine computer controls the position of a fuelmetering device of the engine for the purpose of controlling operationof the engine 3.

As a variant, the selector may include a position dedicated to theidling mode of operation.

Independently of the method applied to request idling operation of theengines of the aircraft, each engine computer can regulate the idlingrating of the associated engine automatically as a function ofoperational and hierarchically ordered conditions:

either through a first mode of regulation by regulating a first speed ofrotation Ng of the gas generator 4;

or through a second mode of regulation by regulating a second speed ofrotation NTL of the free turbine 7 of the engine.

To this end, the computer may take into consideration generation of hotair, then generation of electricity from mechanical power extractionmeans, noise generation, and fuel consumption. The aircraft 1 thusincludes a calculation system 15 having a processor or the equivalentthat executes stored instructions for automatically implementing atleast one idling mode of operation of said engine 3.

With reference to FIG. 2, during a first optimization substep STP 1.1 ofthe idling mode of operation, an original first speed of rotation Ng1 isdetermined that is to be reached for regulating the second speed ofrotation at a level NTLcrit defined by the manufacturer. For example,this level NTLcrit is defined to ensure that the aircraft 1 operatesoutside a ground resonance range, and/or to satisfy operationalconditions. At this stage, said level may, for example, be establishedin order to minimize the noise generation and the fuel consumption ofthe engines.

With reference to FIG. 1, the regulation device may include ameasurement device 65 for measuring outside conditions of thesurroundings in order to determine the altitude of the aircraft and/orthe outside pressure, and the outside temperature.

The avionics computer 30 can then transmit the measurements taken toeach engine computer 20.

Each engine computer 20 then has, in a memory 22, at least onerelationship giving the original speed of rotation Ng1 as a function ofsaid level and of said conditions of the surroundings. Suchrelationships are established by the manufacturer, e.g. by testing.

By using the measurements taken, the avionics computer deduces the firstoriginal speed of rotation Ng1.

In addition, with the aircraft 1 having an electrical network 40 poweredelectrically by the power plant 3′, the regulation device 10 includes ameasurement system 42 for measuring the electricity consumed by theelectrical network 40.

During a second optimization substep STP1.2 that serves to take intoconsideration an operational condition of the electricity generationtype, the avionics computer 30 can determine the magnitude of theelectric current consumed by the aircraft. Said avionics computer 30deduces therefrom an electricity generation target ITOT that each engineshould supply through the associated mechanical power extraction means.The electricity generation target is optionally evaluated in terms oftarget electric current to be delivered.

The avionics computer gives said electricity generation target ITOT toeach engine computer 20.

The engine computer 20 of each engine uses a mathematical modelestablished by the manufacturer, by tests or by some equivalent meansand stored in a memory to determine whether the first original speed ofrotation Ng1 is sufficient to enable the electricity generation targetto be generated.

If it is not sufficient, the idling mode of operation should be managedthrough regulating the first speed of rotation Ng of the gas generator.

Then, during a substep STP1.3.1, the engine computer uses the storedmathematical model to determine a first setpoint speed of rotationNgcons making it possible to deliver the required electricity generationtarget.

In addition, using the measured outside temperature and by means of astored thermal model established by the manufacturer, the enginecomputer determines, during a substep STP1.3.2, a setpoint hot airtemperature THOT to be delivered in order to heat the aircraft and thatserves to take into consideration an operational condition of the hotair generation type. The engine computer deduces therefrom whether thefirst setpoint speed of rotation makes it possible to reach saidsetpoint hot air temperature.

During a substep STP1.3.2.1, if the first setpoint speed of rotationdoes make it possible to reach said setpoint hot air temperature, theengine computer controls the flow rate of fuel delivered to the enginein order to maintain the first speed of rotation equal to the firstsetpoint speed of rotation Ngcons.

Conversely, during a substep STP1.3.2.2.1, if the first setpoint speedof rotation Ngcons does not make it possible to reach said setpoint hotair temperature THOT, the engine computer determines a first targetspeed of rotation Ngcibl making it possible to reach said setpoint hotair temperature.

During a substep STP1.3.2.2.2, the engine computer controls the flowrate of fuel delivered to the engine in order to maintain the firstspeed of rotation Ng equal to the new first target speed of rotationNgcibl.

In addition, if the first original speed of rotation Ng1 of an engine issufficient to enable the electricity generation target to be generated,then, during an optimization substep STP1.4, the engine computerdetermines a setpoint hot air temperature THOT to be delivered to heatthe aircraft, and whether the first original speed of rotation Ng1 makesit possible to reach said setpoint hot air temperature.

During a substep STP1.4.1, if the first original speed of rotation Ng1makes it possible to reach the setpoint hot air temperature THOT, theengine computer 20 of an engine controls the flow rate of fuel deliveredto the engine in order to maintain the second speed of rotation NTL ofthe engine equal to said level NTLcrit.

Conversely, if the first original speed of rotation Ng1 does not make itpossible to reach said setpoint hot air temperature THOT, then, during asubstep STP1.4.2, the engine computer of each engine determines a firstsetpoint speed of rotation Ngcons making it possible to reach saidsetpoint hot air temperature.

During a substep 1.4.3, the engine computer controls the flow rate offuel delivered to the engine in order to maintain the first speed ofrotation Ng equal to the first setpoint speed of rotation Ngcons.

With reference to FIG. 1, the regulation device may also include inhibitmeans 70 for inhibiting the first mode of regulation.

In addition, each engine computer may be connected to measurement meansfor measuring the torque exerted on the outlet shaft of the associatedengine.

Each engine computer has a stop, e.g. a software stop, so as to limitsaid torque to a maximum torque defined by the manufacturer. Thus, eachengine computer limits the flow rate of fuel delivered to the engine inorder to comply with said stop.

LIST OF REFERENCE NUMERALS

-   -   2 Gearbox    -   3 Turbine Engine    -   5 Compressor    -   6 High-Pressure Turbine    -   7 Free Turbine    -   20 Engine Computer    -   21 Computation Unit    -   22 Memory    -   30 Avionics Computer    -   31 Computation Member    -   32 Storage Means    -   41 Electrical Core    -   42 Electricity Consumption Detector    -   50 Collective Pitch Detector    -   55 Ground Detector    -   60 Selector    -   65 External Aircraft Environment Measurement Device    -   100 Mechanical Power Extraction Means    -   STP0 Selection step

STP1.0 Verify whether the collective pitch is less than a threshold andthe aircraft is on the ground

-   -   Implement idling mode of operation when selected and both        criteria are satisfied

FVOL Implement flight mode of operation FVOL when either criteria is notsatisfied

STP1.1 Determine an original gas generator speed of rotation level Ng1to be reached by the gas generator for regulating the speed of rotationNTL of the free turbine at a critical free turbine speed of rotationlevel NTLcrit

STP1.2 Determine whether the power plant can deliver an electricitygeneration target ITOT while the gas generator is operating at theoriginal gas generator speed of rotation level Ng1

STP1.3.1 If the original gas generator speed of rotation level Ng1 isnot sufficient to enable the electricity generation target ITOT to bereached, then determine a setpoint gas generator speed of rotationNgcons that enables the power plant to deliver the electricitygeneration target ITOT

STP1.3.2 Determine a setpoint hot air temperature THOT to be deliveredfor heating the aircraft

STP1.3.2.1 If the setpoint gas generator speed of rotation Ngcons makesit possible to reach the setpoint hot air temperature THOT, then controlthe fuel rate to the engine to maintain the speed of rotation Ng of thegas generator equal to the setpoint gas generator speed of rotationNgcons

STP1.3.2.2.1 If the setpoint gas generator speed of rotation Ngcons doesnot make it possible to reach the setpoint hot air temperature THOT,then determine a target speed of rotation Ngcibl that makes it possibleto reach the setpoint hot air temperature THOT

STP1.3.2.2.2 Control the fuel rate to the engine to maintain the speedof rotation Ng of the gas generator equal to the target speed ofrotation Ngcibl

STP1.4 If the original gas generator speed of rotation level Ng1 issufficient to enable the electricity generation target ITOT to bereached, then determine a setpoint hot air temperature THOT to bedelivered for heating the aircraft and determine whether the originalgas generator speed of rotation level Ng1 makes it possible to reach thesetpoint hot air temperature THOT

STP1.4.1 If the original gas generator speed of rotation level Ng1 makesit possible to reach the setpoint hot air temperature THOT, then controlthe fuel rate to the engine to maintain the speed of rotation NTL of thefree turbine equal to the critical free turbine speed of rotation levelNTLcrit

STP1.4.2 If the original gas generator speed of rotation level Ng1 doesnot make it possible to reach the setpoint hot air temperature THOT,then determine a setpoint gas generator speed of rotation Ngcons thatmakes it possible to reach the setpoint hot air temperature THOT

STP1.4.3 Control the fuel rate to the engine to maintain the speed ofrotation Ng of the gas generator equal to the setpoint gas generatorspeed of rotation Ngcons

Naturally, the present invention may be subjected to numerous variantimplementations. Although several implementations are described, itshould readily be understood that it is not conceivable to identifyexhaustively all possible variants. Naturally, it is possible to replaceany described component with equivalent means without going beyond theambit of the present invention.

What is claimed is:
 1. A regulator device for automatically regulating apower plant of an aircraft having a rotary wing and a turbine engine,the turbine engine being operable in an idling mode of operation andhaving a gas generator and a free turbine, the regulator devicecomprising: a computer system configured to control the turbine engine,the computer system further configured to, while implementation of theidling mode of operation is requested and the aircraft is standing onground, implement the idling mode of operation and operate the turbineengine in compliance with the idling mode of operation as a function ofa plurality of operational and hierarchically ordered conditions eitherthrough: a first mode of regulation by regulating a speed of rotation(Ng) of the gas generator; or a second mode of regulation by regulatinga speed of rotation (NTL) of the free turbine; wherein while the idlingmode of operation is implemented, the computer system is furtherconfigured to: determine an original gas generator speed of rotationlevel (Ng1) that is to be reached by the gas generator for regulatingthe speed of rotation (NTL) of the free turbine at a critical freeturbine speed of rotation level (NTLcrit) defined by a manufacturer tosatisfy a first one of the operational and hierarchically orderedconditions; and determine an electricity generation target (ITOT) thatthe power plant is to deliver to satisfy a second one of the operationaland hierarchically ordered conditions; wherein while the idling mode ofoperation is implemented and the power plant cannot deliver theelectricity generation target (ITOT) while the gas generator isoperating at the original gas generator speed of rotation level (Ng1),the computer system is further configured to: determine a setpoint hotair temperature (THOT) that is to be delivered for heating the aircraftto satisfy a third one of the operational and hierarchically orderedconditions; determine a setpoint gas generator speed of rotation(Ngcons) that makes it possible to deliver the electricity generationtarget (ITOT); determine whether the setpoint gas generator speed ofrotation (Ngcons) makes it possible to reach the setpoint hot airtemperature (THOT); when the setpoint gas generator speed of rotation(Ngcons) makes it possible to reach the setpoint hot air temperature,operate the turbine engine in compliance with the idling mode ofoperation by automatically regulating the speed of rotation (Ng) of thegas generator to maintain the speed of rotation (Ng) of the gasgenerator equal to the setpoint gas generator speed of rotation(Ngcons); and when the setpoint gas generator speed of rotation (Ngcons)does not make it possible to reach the setpoint hot air temperature(THOT), operate the turbine engine in compliance with the idling mode ofoperation by automatically regulating the speed of rotation (Ng) of thegas generator to maintain the speed of rotation (Ng) of the gasgenerator equal to a target gas generator speed of rotation that makesit possible to reach the setpoint hot air temperature (THOT).
 2. Theregulator device of claim 1 wherein: the computer system includes atleast one of an avionics computer and an engine computer; and theturbine engine is operated by the computer system during a period of theidling mode of operation through the first mode of regulation and duringanother period of the idling mode of operation through the second modeof regulation.
 3. The regulator device of claim 1 further comprising: aselector for requesting implementation of the idling mode of operation;and wherein the computer system is connected to the selector.
 4. Theregulator device of claim 3 wherein: the computer system includes anavionics computer and an engine computer connected to one another, theavionics computer being further connected to a determination systemconfigured to determine a collective pitch of the rotary wing, adetermination device configured to determine a state in which theaircraft is standing on ground, and the selector.
 5. The regulatordevice of claim 1, wherein the aircraft has an electrical networkelectrically powered by the power plant, the regulator device furthercomprising: a measurement system configured to measure electricityconsumed by the electrical network.
 6. The regulator device of claim 1further comprising: a measurement device for measuring conditions ofsurroundings outside the aircraft to determine a setpoint hot airtemperature for heating the aircraft.
 7. The regulator device of claim 1wherein: the computer system further configured to select theoperational and hierarchically ordered conditions to be taken intoconsideration in operating the turbine engine in compliance with theidling mode of operation from a list of operational conditionsincluding: generation of hot air from the turbine engine for heating theaircraft as a function of outside conditions; generation of electricityfrom the gas generator for electrically powering the aircraft;minimization of noise emission; and minimization of fuel consumption. 8.The regulator device of claim 7 wherein: the computer system is furtherconfigured to establish the operational and hierarchically orderedconditions in a hierarchical order selected by an operator of theaircraft.
 9. The regulator device of claim 1 wherein: the operationaland hierarchically ordered conditions include the following operationalconditions in the following hierarchical order of priority: a first oneof the operational conditions: generation of hot air from the turbineengine for heating the aircraft as a function of outside conditions; asecond one of the operational conditions: generation of electricity fromthe gas generator for electrically powering the aircraft; a third secondone of the operational conditions: minimization of noise emission; and afourth one of the operational conditions: minimization of fuelconsumption.
 10. The regulator device of claim 1 wherein: the criticalfree turbine speed of rotation level (NTLcrit) is defined to ensure thatthe aircraft operates outside a ground resonance range by minimizingnoise emission and fuel consumption by the turbine engine.
 11. Theregulator device of claim 1 wherein: the computer system is furtherconfigured to inhibit the first mode of regulation in response to amanual selection of the second mode of regulation.
 12. The regulatordevice of claim 1 wherein: the computer system is further configured toimplement a torque stop to limit torque developed by an outlet shaft ofthe turbine engine when the turbine engine is operating in the secondmode of regulation.
 13. A regulator device for automatically regulatinga power plant of an aircraft having a rotary wing and a turbine engine,the turbine engine being operable in an idling mode of operation andhaving a gas generator and a free turbine, the regulator devicecomprising: a computer system configured to control the turbine engine,the computer system further configured to, while implementation of theidling mode of operation is requested and the aircraft is standing onground, implement the idling mode of operation and operate the turbineengine in compliance with the idling mode of operation as a function ofa plurality of operational and hierarchically ordered conditions eitherthrough: a first mode of regulation by regulating a speed of rotation(Ng) of the gas generator; or a second mode of regulation by regulatinga speed of rotation (NTL) of the free turbine; wherein while the idlingmode of operation is implemented, the computer system is furtherconfigured to: determine an original gas generator speed of rotationlevel (Ng1) that is to be reached by the gas generator for regulatingthe speed of rotation (NTL) of the free turbine at a critical freeturbine speed of rotation level (NTLcrit) defined by a manufacturer tosatisfy a first one of the operational and hierarchically orderedconditions; determine an electricity generation target (ITOT) that thepower plant is to deliver to satisfy a second one of the operational andhierarchically ordered conditions; and when the power plant cannotdeliver the electricity generation target while the gas generator isoperating at the original gas generator speed of rotation level (Ng1),operate the turbine engine in compliance with the idling mode ofoperation by automatically regulating the speed of rotation (Ng) of thegas generator; wherein while the idling mode of operation is implementedand the power plant can deliver the electricity generation target (ITOT)while the gas generator is operating at the original gas generator speedof rotation level (Ng1), the computer system is further configured to:determine a setpoint hot air temperature (THOT) that is to be deliveredfor heating the aircraft to satisfy a third one of the operational andhierarchically ordered conditions; when the original gas generator speedof rotation level (Ng1) makes it possible to reach the setpoint hot airtemperature (THOT), operate the turbine engine in compliance with theidling mode of operation by automatically regulating the speed ofrotation (NTL) of the free turbine to maintain the speed of rotation(NTL) of the free turbine equal to the critical free turbine speed ofrotation level (NTLcrit); and when the original gas generator speed ofrotation level (Ng1) does not make it possible to reach the setpoint hotair temperature (THOT), determine a setpoint gas generator speed ofrotation (Ngcons) that makes it possible to reach the setpoint hot airtemperature (THOT) and operate the turbine engine in compliance with theidling mode of operation by automatically regulating the speed ofrotation (Ng) of the gas generator to maintain the speed of rotation(Ng) of the gas generator equal to the setpoint gas generator speed ofrotation (Ngcons).
 14. The regulator device of claim 13 wherein: thecomputer system includes at least one of an avionics computer and anengine computer; and the turbine engine is operated by the computersystem during a period of the idling mode of operation through the firstmode of regulation and during another period of the idling mode ofoperation through the second mode of regulation.
 15. The regulatordevice of claim 13 further comprising: a selector for requestingimplementation of the idling mode of operation; and wherein the computersystem is connected to the selector.
 16. The regulator device of claim15 wherein: the computer system includes an avionics computer and anengine computer connected to one another, the avionics computer beingfurther connected to a determination system configured to determine acollective pitch of the rotary wing, a determination device configuredto determine a state in which the aircraft is standing on ground, andthe selector.
 17. The regulator device of claim 13 wherein: the computersystem further configured to select the operational and hierarchicallyordered conditions to be taken into consideration in operating theturbine engine in compliance with the idling mode of operation from alist of operational conditions including: generation of hot air from theturbine engine for heating the aircraft as a function of outsideconditions; generation of electricity from the gas generator forelectrically powering the aircraft; minimization of noise emission; andminimization of fuel consumption.
 18. The regulator device of claim 17wherein: the computer system is further configured to establish theoperational and hierarchically ordered conditions in a hierarchicalorder selected by an operator of the aircraft.
 19. An aircraftcomprising: a rotary wing; a power plant having a turbine engine fordriving the rotary wing, the turbine engine being operable in an idlingmode of operation and having a gas generator and a free turbine; and aregulator device, the regulator device including: a selector forrequesting implementation of the idling mode of operation; a computersystem connected to the selector and configured to control the turbineengine; and the computer system, while implementation of the idling modeof operation is requested and the aircraft is standing on ground,automatically implements the idling mode of operation and operates theturbine engine in compliance with the idling mode of operation as afunction of operational and hierarchically ordered conditions eitherthrough: a first mode of regulation by regulating a speed of rotation(Ng) of the gas generator; or a second mode of regulation by regulatinga speed of rotation (NTL) of the free turbine; wherein while the idlingmode of operation is implemented, the computer system of the regulatordevice is further configured to: determine an original gas generatorspeed of rotation level (Ng1) that is to be reached by the gas generatorfor regulating the speed of rotation (NTL) of the free turbine at acritical free turbine speed of rotation level (NTLcrit) defined by amanufacturer to satisfy a first one of the operational andhierarchically ordered conditions; and determine an electricitygeneration target (ITOT) that the power plant is to deliver to satisfy asecond one of the operational and hierarchically ordered conditions;wherein while the idling mode of operation is implemented and the powerplant cannot deliver the electricity generation target (ITOT) while thegas generator is operating at the original gas generator speed ofrotation level (Ng1), the computer system of the regulator device isfurther configured to: determine a setpoint hot air temperature (THOT)that is to be delivered for heating the aircraft to satisfy a third oneof the operational and hierarchically ordered conditions; determine afirst setpoint gas generator speed of rotation (Ngcons1) that makes itpossible to deliver the electricity generation target (ITOT); determinewhether the first setpoint gas generator speed of rotation (Ngconsl)makes it possible to reach the setpoint hot air temperature (THOT); whenthe first setpoint gas generator speed of rotation (Ngconsl) makes itpossible to reach the setpoint hot air temperature, operate the turbineengine in compliance with the idling mode of operation by automaticallyregulating the speed of rotation (Ng) of the gas generator to maintainthe speed of rotation (Ng) of the gas generator equal to the firstsetpoint gas generator speed of rotation (Ngconsl); and when thesetpoint gas generator speed of rotation (Ngcons) does not make itpossible to reach the setpoint hot air temperature (THOT), operate theturbine engine in compliance with the idling mode of operation byautomatically regulating the speed of rotation (Ng) of the gas generatorto maintain the speed of rotation (Ng) of the gas generator equal to atarget gas generator speed of rotation that makes it possible to reachthe setpoint hot air temperature (THOT).
 20. The aircraft of claim 19wherein: while the idling mode of operation is implemented and the powerplant can deliver the electricity generation target (ITOT) while the gasgenerator is operating at the original gas generator speed of rotationlevel (Ng1), the computer system of the regulator device is furtherconfigured to: determine a setpoint hot air temperature (THOT) that isto be delivered for heating the aircraft to satisfy a third one of theoperational and hierarchically ordered conditions; when the original gasgenerator speed of rotation level (Ng1) makes it possible to reach thesetpoint hot air temperature (THOT), operate the turbine engine incompliance with the idling mode of operation by automatically regulatingthe speed of rotation (NTL) of the free turbine to maintain the speed ofrotation (NTL) of the free turbine equal to the critical free turbinespeed of rotation level (NTLcrit); and when the original gas generatorspeed of rotation level (Ng1) does not make it possible to reach thesetpoint hot air temperature (THOT), determine a second setpoint gasgenerator speed of rotation (Ngcons2) that makes it possible to reachthe setpoint hot air temperature (THOT) and operate the turbine enginein compliance with the idling mode of operation by automaticallyregulating the speed of rotation (Ng) of the gas generator to maintainthe speed of rotation (Ng) of the gas generator equal to the secondsetpoint gas generator speed of rotation (Ngcons2) gas generator speedof rotation (Ngcons).